1. Field of the Invention
The invention relates to a hand-held transmitting and/or receiving apparatus including a housing made of an electrically non-conductive material, an electric circuit inside the housing, an electrical ground plane inside the housing made from non-conductive material, an antenna resonator element extending approximately parallel to the ground plane and having a first free end and a second end electrically connected by a ground connector to the ground plane and a device for connecting the ground plane and the resonant element to the electric circuit.
2. Description of the Prior Art
Hand held transmitting and receiving devices are well known. Such a device is disclosed in European Patent No. EP 0 484 454 B1 where an antenna resonant element has the form of an angled metal sheet of metal foil applied on the outside of a plastic housing. An electrical ground plane has the form of a shielding housing positioned inside the plastic housing which shielding housing contains the electric circuit. Between the shielding housing and the plastic housing and in the area of the antenna resonant element is an air gap. A grounding lead extends through a slit in the plastic housing and connects the angled leg of the L-shaped antenna resonant element to the shielding housing.
This apparatus has the disadvantage that it is difficult to form the slit in the plastic housing for the lead to extend through. Either the slit must be formed when forming the housing or the slit has to be cut after the housing is formed. Furthermore, it is difficult to provide the ground connector leading through the slit and to connect it to the antenna resonant element at one end and to the shielding housing inside the plastic housing at the other end.
An important electrical disadvantage of this known apparatus results from the air gap between the shielding housing and the plastic housing on which an antenna resonant element is fixed. The electrical parameters of the resonant element are influenced by this air gap. Since tolerances of the dimensions of this air gap and changes due to mechanical and thermal influences are unavoidable it is not possible to keep the electrical parameters of the antenna constant. This results in mismatching, standing waves on the feed line to the antenna and changes of the radiation pattern.